An innovative approach to improving water quality

Mar. 23, 2014 @ 10:12 AM

Later this week, leaders in the development and construction industries, landscape designers and planning and regulatory officials will gather for a two-day conference in Raleigh to discuss low-impact development.  The conference will highlight innovative technologies and tools for implementing low-impact development, including the use of green infrastructure. Integrating green infrastructure into new and existing development represents a growing practice in place of traditional stormwater pollution controls.

Green infrastructure, which utilizes soils, vegetation and natural processes to reduce stormwater pollution, is a critical tool in protecting water quality in urban watersheds. It is designed to capture the water that runs off of our streets, driveways and roofs during rain storms.  These systems or practices, such as rain gardens, green roofs, permeable pavement and setting aside open space in urban areas, reduce stormwater flow by allowing water to infiltrate into the soil and evaporating the water by the green vegetation.

At every level of government, environmental managers are recognizing the benefits of green infrastructure and taking steps to encourage its use.  At the federal level the U.S. Environmental Protection Agency’s (EPA) most recent strategic plan identifies green infrastructure as a key component in “improving water quality while also enhancing the vitality of communities.” 

Through EPA’s Green Infrastructure Funding program the agency is investing millions of dollars to help restore urban watersheds and support community revitalization.  The program funding includes a recent award for a project developed by Durham’s Ellerbe Creek Watershed Association.  This project will create a green infrastructure plan to contribute to the restoration of water quality in Ellerbe Creek, which drains into Falls Lake, and is not meeting federal water quality standards.

State and local officials are also promoting the use of green infrastructure.  The N.C. Department of Environment and Natural Resources has developed a process that provides the flexibility for developers seeking to use green infrastructure to obtain pollution reduction credits under stormwater permits.  At the local level, city officials in Durham have implemented a pilot program, Rain Catchers, that installs rain gardens, cisterns and other rain-catching devices at residential lots in some of the city’s downtown neighborhoods. 

The work by environmental management officials is being supported by academic research.  Scientists at the UNC Institute for the Environment and the Renaissance Computing Institute (RENCI) are collaborating with researchers across the country to increase the understanding of the role green infrastructure can play to reduce stormwater pollution in urban watersheds.  These researchers are partnering with stormwater managers in Baltimore, Chicago, Phoenix, Portland and right here in Durham.  The research, funded by the National Science Foundation, will develop design and assessment tools to help managers and researchers evaluate the sustainability and success of urban green infrastructure systems across different climatic and geologic settings.

This research is grounded in the concept that designing the right size and placement of a green infrastructure system, such as a rain garden, is critical to ensuring that the system functions properly and reduces stormwater flow.  Critically, this design must balance the needs of the community --residents and neighbors must view the system as an amenity and not as an eyesore -- or the adoption of green infrastructure systems will be limited.

One of the first tools being developed allows web-based visualization of specific green infrastructure systems on the landscape, whether in a resident’s yard or in the context of the entire neighborhood.  This tool will allow stormwater engineers, planners and homeowners to experiment with different types and designs of green infrastructure within a community.  In addition to the visualization component, the tool will evaluate system performance in reducing stormwater. 

The upcoming low-impact development conference in Raleigh will further the development community’s ability to implement innovative designs and cutting-edge practices, such as the installation of green infrastructure systems.  The use of green infrastructure systems at the neighborhood scale as well as at individual homes to improve water quality is a growing trend nationwide -- with Durham helping to lead the way.  Much of that success can be attributed to ongoing collaboration between developers, environmental officials and academic researchers.  

Larry Band is a distinguished professor in the Department of Geography at the University of North Carolina-Chapel Hill and the director of the UNC Institute for the Environment.  Steve Wall is a translational and policy research associate in the Institute.